A pipe bomb next to two propane tanks were found in a Littleton, Colorado mall on the anniversary of the Colombine school shooting.
Crime scene tape was removed and Southwest Plaza Mall in Littleton Colorado re-opened Thursday.
There was little evidence of the chaotic scene there Wednesday.
Thousands of shoppers were evacuated after firemen responding to a small fire, found a pipe bomb sitting next to two canisters of propane gas.
Investigators today know more, but still not enough to make an arrest.
The FBI and ATF have joined the investigation which for now is focusing on the man in the photos taken by mall security cameras.
Those photos show him entering through a mall door, not intended for public use, and near where the pipe bomb was found.
Wednesday's incident occurred a mile and a half away from and exactly 12 years after the deadly Columbine High School shooting.
But police aren't willing to link the two just yet.
"There's not a definite link to what happened at columbine...other than date, time and proximity…" said Jefferson County Sheriff Ted Mink.
But an eerie coincidence to the Columbine killers: they also planned to detonate propane filled canisters.
Chris Clackum, NBC News.